title: A retinoblastoma susceptibility gene product, RB, targeting protease is regulated through the cell cycle.
abstract: Degradation of cyclin B and cyclin-dependent kinase inhibitor, p27, at a specific time has been shown to play a critical role in regulating the cell cycle. SPase, a nuclear and cytosol protease with cathepsin B- and L-like proteolytic activity, has been identified in several cell lines. This proteolytic enzyme selectively degraded nuclear proteins such as retinoblastoma susceptibility gene product, RB, and transcription factor, SP-1. High levels of SPase activity were detected at the G1/S, moderate levels at the G1 and S phases, and undetectable activity at the M phase of synchronized CV-1 cells, suggesting that SPase activity is regulated through the cell cycle. Degradation of RB correlated with SPase activity throughout the cell cycle, suggesting that SPase regulates RB, which has a functional role in regulating cell cycle. These results demonstrated that SPase plays an integral role in regulating the nuclear regulator, RB, in controlling cell cycle progression.
authors.affiliation: Department of Surgery, School of Medicine, University of California, Los Angeles, 90095-1782, USA.
authors.forename: Y H
authors.initials: YH
authors.lastname: Fu
authors.forename: T
authors.initials: T
authors.lastname: Nishinaka
authors.forename: K
authors.initials: K
authors.lastname: Yokoyama
authors.forename: R
authors.initials: R
authors.lastname: Chiu
mesh_terms: D000818:Animals; D019556:COS Cells; D002401:Cathepsin B / Q000378:metabolism; D056668:Cathepsin L; D002403:Cathepsins / Q000378:metabolism; D002453:Cell Cycle; D002460:Cell Line; D002467:Cell Nucleus / Q000201:enzymology; D002522:Chlorocebus aethiops; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D003600:Cytosol / Q000201:enzymology; D010450:Endopeptidases; D006706:Homeostasis; D007668:Kidney; D016160:Retinoblastoma Protein / Q000378:metabolism*; D016329:Sp1 Transcription Factor / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D016160:Retinoblastoma Protein; D016329:Sp1 Transcription Factor; D002403:Cathepsins; D010450:Endopeptidases; C105586:CV-1 SPase; D003546:Cysteine Endopeptidases; D002401:Cathepsin B; D056668:Cathepsin L